Pesticide “DDT” Derivative Found in Several WA Cannabis Products

The Washington State Liquor and Cannabis Board (“WSLCB”) sent an alert on Thursday, April 6, notifying cannabis licensees of a pattern of pesticide testing failures in Okanogan County. The WSLCB detected several instances of products containing dichlorodiphenyldichloroethylene (“DDE”) through random pesticide testing and many exceed action levels.

The WSLCB is taking the following immediate action to address the issue, which will specifically affect 18 licensees in Okanogan County:

  • “Placing administrative holds on licensees in the affected geographic area with above actionable limits of DDE;
  • Upon confirmation that DDE exists in the soil in this region, placing administrative holds on all licensees in the geographic area;
  • Requesting a list of all products distributed since August 2022 from all licensees in the geographic area;
  • Securing and testing on-shelf products from all 18 licensees in the geographical area; and
  • Requesting the licensees in the geographic area with DDE tests above actionable limits conduct a licensee-initiated recall on all products.”

What is DDE?

DDE is a derivative chemical that forms following the breakdown of the infamous “DDT” (dichlorodiphenyltrichloroethane) that was widely used in the U.S. as a pesticide until it was banned in 1972. According to the Centers for Disease Control, “Microorganisms in the soil slowly break down DDT (it can take anywhere from 2 to 15 years to break down half of the DDT)”.

The CDC states that risk for exposure is low and most exposures occur from eating contaminated foods. Further, people that swallow large amounts of the chemical had tremors, headaches, nausea, and seizures, though no effects were noticed when people took a small dose over the course of 18 months. People with higher levels of the chemical in their blood have an increased risk of liver cancer.

Both DDT and DDE are considered legacy contaminants–chemicals once used in the U.S. but then discontinued or made illegal under US law. Legacy contaminants often linger in soil and water long after they were initially used on the site or made their way to a particular site from another location. Legacy chemicals once used on a particular plot of land say, can “resuspend” years later and through soilborne drift, land on other properties. Similarly, soil and sediment lifecycles could result in latent legacy contaminants re-emerging and contaminating crops long after their initial use.

There seems to be ample evidence of DDT being widely used in Washington, particularly in orchards and vineyards on the eastern slope of the Cascades. According to a 2008 research paper investigating DDT and DDE levels in Lake Chelan, WA, “DDT was commonly used at Washington orchards from about 1946 to 1970, with high application rates (citation removed) being documented for eastern Washington orchards in the vicinity of Lake Chelan.” For reference, Omak, the largest city in Okanogan County, is around 60 miles from Lake Chelan.

How did the DDE exposure occur?

It appears that the producers in Okanogan County are dealing with the reemergence of pre-existing, latent DDT (now broken down to DDE) on their properties. As the WSLCB stated in its alert “The cannabis crop possesses a unique vulnerability with respect to environmental contamination. The plants can absorb contaminants such as pesticides and heavy metals to a much higher degree than many other plants.”

Pesticide testing of cannabis in Washington

As we wrote about here, Washington enacted a pesticide and heavy metals testing regime for cannabis in March of 2022. The pesticide action level rule lists 59 allowable pesticide compounds and their acceptable thresholds that cannabis products must be screened for before they can be sold. DDT and its derivative DDE are not contained on the list of compounds that are screened for. The WSLCB acknowledged this in its alert that “state-certified cannabis-testing labs are not required to screen for DDE among the 59 pesticides included in mandatory testing because DDE contamination above actionable levels has not emerged elsewhere”.

So how did the state catch the DDE in the cannabis products in this case? The state has been conducting random testing of cannabis products for several years. But the screening that randomly selected products are subject to is considerably more comprehensive than the mandatory testing all cannabis products must be tested for under Washington Annotated Code section 314-55-109. The LCB stated in its alert that it “contracts with the state Dept. of Agriculture (WSDA) … to perform pesticide tests. The WSDA lab can currently detect 243 pesticides. Their testing includes DDT and its breakdown products such as DDE.”

This begs the question of why DDT and DDE are contained in the WSDA screening procedures and not the mandatory pesticide screening procedures under WAC 314-55-109, particularly when the WSLCB acknowledged that cannabis plants are uniquely vulnerable to such contamination. The answer probably lies in not having the resources to subject all cannabis product testing to the more comprehensive WSDA testing procedures. Nonetheless, given the well-known and widespread use of DDT in Washington, it seems like DDT and DDE at least deserved to make the cut given their latent and reemergent characteristics.


The 18 licensees within the “affected area” are going to have a tough time surviving the administrative action being taken by the state. It seems probable given the historically widespread use of DDT in the region that at least some of the soil samples the WSLCB plan to take will come back contaminated. The result of that will be administrative holds for all 18 licensees. What happens thereafter is unclear.

Further, all licensees products will be tested for DDE contamination and for those that have a product fail, a recall of all of their products will be required. I’m not suggesting that this action shouldn’t be taken. No one wants to consume contaminated cannabis products. But the fact remains that this administrative action is going to be devastating.

If your outdoor grow operation is in historically orchard and vineyard country, this issue may affect you. We don’t know at this time what the state’s regulatory response will be but the chances of it being nominal are slim. The prevalence of DDT use in the state may mandate a regulatory response affecting cannabis testing in the entire state.

We’ll be following developments here.

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